It is known to use apply and release chambers in a torque converter to control a lock-up clutch. For example, fluid pressure in the apply chamber is increased with respect to fluid pressure in the release chamber to close the clutch and, conversely, fluid pressure in the release chamber is increased with respect to fluid pressure in the apply chamber to open the clutch.
In some applications, it is desirable to keep the clutch engaged when the torque converter is in coast mode, that is, a transmission for a vehicle housing the torque converter is applying torque to an engine for the vehicle. To accomplish this, fluid pressure in the apply chamber must be kept higher than fluid pressure in the release chamber. However, due to the fluid currents generated by the coast mode and the fluid communication between the release and apply chambers noted above, fluid flows from the apply chamber to the release chamber. This fluid flow may result in the fluid pressure in the release chamber being greater than the fluid pressure in the apply chamber, which prevents the clutch from closing.
FIG. 5 is a partial cross-sectional view of a prior art seal arrangement to isolate apply and release chambers for a clutch. Commonly owned U.S. Patent Application Publication No. 2008/0277228 uses retainer 43 connected to cover 5 with rivets 52 to retain seal 42, as shown in FIG. 5. However, this arrangement requires fabricating rivets from the cover and increases the axial extent of the clutch, since the retainer is offset from the seal in the axial direction.